John and I were just talking with a client about narrowing the market focus for a somewhat generic business application he's developing. He's a smart guy, and he really gets it. In fact, he came up with the perfect story for explaining exactly why and how focus works.
He told us that when his kids were small, he took them and their grandfather out to a farm to pick strawberries. Their grandfather sat in one place and picked a couple of gallons of strawberries. During the same amount of time, the kids ran around and each picked about a quart.
This is the singular best explanation of the importance of focus that I've ever heard.